New technique developed to detect elusive, endangered dolphins

Published: Friday, February 22, 2008, 16:08 [IST]

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New Delhi, Feb 22 (UNI) A new technique has been developed to detect accurately the presence of dolphins in various rivers, which would go a long way in the conservation of the endangered animal, whose number in the country has been reduced to just between 1800 and 2000.

The new method of counting the number of the elusive animal is based on accoustic signals and has been developed by the World Wildlife Fund(WWF)-India and the University of Tokyo.

The accoustic survey is as accurate as the visual survey and it can done by a small set of instruments. It requires a boat, a set of hydrophones and a computer and a server. The hydrophones, which are submerged into water, observe the underwater behaviour of dolphins in a large area of the river, and then send the data over the commercial mobile network to a webserver.

A team, which tried the technique for the second time in the Ganga last week, used six hydrophones and could successfully detect dolphin activity during the day and night when visual observations were not possible.

The compact handheld audio-based click detector was also tried for the first time, This device can be operated from a moving boat and is a convenient aid for the user to quickly locate the presence of dolphins.

Making a presentation on the accoustic survey, Prof Tamaki Ura of the University of Tokyo, who was part of the team that developed the new technique, said the method was so simple that even a lay person could be trained to use it.

He said that 70 to 80 per cent dolphins could be found by conducting a survey through this technique which is called Passive Sonar Technique.

Later, talking to reporters, Dr Sandeep Behera, the coordinator, Fresh and Wetlands Programme of WWF, said the technique could do the job of counting the number and determining the location of dolphins in a few days, while going by visual method, it took him 20 years to do it.

He said the number of dolphins had been on a constant decline due to various reasons, mainly because of the degradation of their habitat due to construction of dams and barrages which constrained their movement and conseqently chances of cross breeding.

The depleting water level and excessive fishing has also responsible for the decline in dolphin population, he said.

Dr Behera said the presence of dolphins in water was and indicator of the freshness of water as the animal could not survive except in fresh water.

Since it was a mammal, its presence in water was indicative of the suitability of that water for human beings, he said.